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Abstract

Electron spins in silicon quantum dots are attractive systems for quantum computing owing to their long coherence times and the promise of rapid scaling of the number of dots in a system using semiconductor fabrication techniques. Although nearest-neighbour exchange coupling of two spins has been demonstrated, the interaction of spins via microwave-frequency photons could enable long-distance spin–spin coupling and connections between arbitrary pairs of qubits (‘all-to-all’ connectivity) in a spin-based quantum processor. Realizing coherent spin–photon coupling is challenging because of the small magnetic-dipole moment of a single spin, which limits magnetic-dipole coupling rates to less than 1 kilohertz. Here we demonstrate strong coupling between a single spin in silicon and a single microwave-frequency photon, with spin–photon coupling rates of more than 10 megahertz. The mechanism that enables the coherent spin–photon interactions is based on spin–charge hybridization in the presence of a magnetic-field gradient. In addition to spin–photon coupling, we demonstrate coherent control and dispersive readout of a single spin. These results open up a direct path to entangling single spins using microwave-frequency photons.

Acknowledgements

We thank A. J. Sigillito for technical assistance and M. J. Gullans for discussions. This work was supported by the US Department of Defense under contract H98230-15-C0453, Army Research Office grant W911NF-15-1-0149, and the Gordon and Betty Moore Foundations EPiQS Initiative through grant GBMF4535. Devices were fabricated in the Princeton University Quantum Device Nanofabrication Laboratory.

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Contributions

X.M. fabricated the sample and performed the measurements. X.M., D.M.Z. and J.R.P. developed the design and fabrication process for the DQD. X.M. and S.P. developed the niobium cavity fabrication process. M.B., G.B., J.M.T. and J.R.P. developed the theory for the experiment. X.M., M.B. and J.M.T. analysed the data. X.M., J.R.P., G.B. and J.M.T. wrote the manuscript with input from the other authors. J.R.P. planned and supervised the experiment.

Competing interests

X.M., J.R.P., D.M.Z. and Princeton University have filed a provisional US patent application related to spin–photon transduction.